Fewer than 50% of elderly depressed patients achieve remission and functional recovery in response to first-line antidepressant pharmacotherapy. The majority of patients are left with significant residual symptoms, putting them at risk of chronic illness, frailty, social isolation, and suicide. Complementary mind-body interventions are hypothesized to improve partial remission to antidepressants via stress-reduction, improved physical functioning, increased socialization, and reduced risks of polypharmacy. However, there are no studies of mind-body interventions, such as Tai Chi Chih (TCC), used to complement the first-line standard drug treatment to enhance symptomatic remission and functional recovery in older depressed individuals who had only partial or no response to the first-line treatment. The proposed randomized parallel- group comparison trial builds on our preliminary studies of antidepressant response in the elderly, and the use of TCC to enhance physical functioning in older adults. It aims to investigate whether complementary treatment with TCC will be superior to using the Health Education (HE) control condition added to an optimal dose of escitalopram in bringing partial remitters to the first-line treatment to symptomatic remission, and in improving health-related quality of life, life satisfaction, and functional disability. We will recruit and treat 148 subjects with major depression aged 65 and older using 10 mg of escitalopram for the first eight weeks. Subjects who are partial remitters to escitalopram will continue to receive 10 mg a day of escitalopram, and will also be randomly assigned to 8 weeks of either complementary use of TCC for 60 minutes twice a week, or to the Health Education program for 120 minutes once a week. Subjects will receive comprehensive evaluations of depression, health-related quality of life, life satisfaction, and disability. Changes over time in measures of depressive symptoms, disability, quality of life, and life satisfaction will be assessed in the statistical models. We will explore the role of proinflammatory cytokines in the underlying mechanisms of treatment response. The proposed study will yield important results with regard to the complementary use of Tai Chi Chih to treat geriatric depression, and it will provide the preliminary data on the proposed mechanisms of treatment response. Public Health Relevance: Our study will identify older subjects with major depression who respond only partially to the standard first-line antidepressant treatment with escitalopram. We will randomize partial responders to the Tai Chi Chih (TCC) or Health Education to complement the first-line treatment in partial responders in order to improve the rates of symptomatic remission and functional recovery. We will explore the role of proinflammatory cytokines in treatment response. This will be the first randomized trial of geriatric depression evaluating the efficacy of a complementary mind-body intervention with TCC augmenting the standard antidepressant treatment to achieve symptomatic remission and functional recovery.